Renewable energy sources are preferable for many ocean-based systems. As an example, solar, wind, and wave driven energy systems may be suitable for near-surface oceanographic sensors and monitoring stations. For submerged and ocean-floor applications however, such energy sources are not viable. Rather, geothermal, sediment, or ocean current conditions must be relied upon. Accordingly, there is a need for a compact and reliable system that can harness ocean energy to provide a renewable power source for submerged ocean-based systems.